Amputees commonly use prosthetic devices to improve their mobility and associated quality of life. Various types of prostheses exist for replacing the functionality of a missing limb. Transtibial and transfemoral prostheses are effective at helping amputees regain the ability to walk on their own. Various forces cause separation between a prosthetic limb and a residual limb, especially during use. This may happen during the swing phase of ambulation, when a prosthetic leg is subjected to both gravitational and centrifugal forces.
The manner in which an artificial limb is attached to a residual limb determines the control an amputee has over the prosthesis. Traditionally, prostheses are secured to amputees' residual limbs by straps, belts, cuffs, harnesses and/or locking pins. These devices are inconvenient and uncomfortable. They cause chafing against the patient's body, which leads to sores and abrasions. It is now common to use some type of suspension system.
Amputees can secure prosthetic devices on their residual limbs by using various vacuum or suction arrangements, whereby the maximum strength of the force holding the prosthesis to the residual limb is a function of the atmospheric pressure. The differential air pressure is routinely referred to as suction or vacuum by those having skill in the art. To maintain the sub-atmospheric pressure created within the distal end of the socket, sealing sleeves or liners have been provided to prevent an influx of air around the distal end of the residual limb. Such liners are provided between the residual limb and the socket to provide for slight compression, and a gripping connection is provided to assist with the suction suspension.
The liner can be rolled onto the residual limb so the liner-covered limb can then be inserted into the prosthetic socket. The use of conventional liners alone only provides a partial suction fit since they do not form a true air-tight seal with the socket. Some air will slowly enter the socket, especially during the swing phase of the patient's gait and during periods of inactivity.
Conventional vacuum systems have been used to increase the suction within the socket. Such vacuum systems may utilize a valve at a distal end of an otherwise closed socket arranged to receive the distal end portion of a residual limb. These pressure-control systems work by exhausting air only from the space between the distal end of the residual limb and the distal end of the socket interior as the limb is fully inserted into the socket. Any air that has migrated to areas other than the distal end can remain trapped, and this action affects the optimal pressure differential and diminishes the strength of the suction connection. There is a clear need to provide a way to allow a user to expel air from within any area of the socket.
The use of a valve is intended to allow air to be expelled from the socket in order to maintain at least a slight negative pressure for creating suction against the residual limb. Although the swing phase of the gait cycle will tend to pull the socket off the limb, walking and other weight-bearing activities may push the limb further into the socket. Pushing the limb further into the socket causes the valve to expel air. Conversely, directly pulling the limb out of the socket is prohibited due to the effect of suction.
Common valve systems used with prosthetic sockets have included an inner base connected to an outer housing that can be threaded directly to the socket wall. These types of valve systems often fail at maintaining the desired air pressure within the socket because they are installed on flat socket wall surfaces. The inclusion of a threaded outer housing helps to prevent air from leaking out of the socket from around the housing instead of being expelled through the valve as intended. Without an air-tight seal in a vacuum suspension system, any significant loss of suction will cause separation of the prosthesis from the residual limb. Thus there is a clear need to provide a valve arranged in a suspension system that can be adapted for effective use on a curved portion of a socket wall surface.
Other traditional sockets may include a separate, self-contained vacuum reservoir for maintaining the sub-atmospheric pressure within the socket interior. However, the vacuum systems create additional bulk and add weight to the socket, making it more difficult for an amputee to achieve natural mobility with the attached prosthetic. Attaching such a reservoir may also decrease the structural integrity of the socket since it may no longer conform to the residual limb and provide a smooth and comfortable fit if it collapses.
It has been found that total contact between a residual limb and a prosthetic socket is important to attain an even weight distribution of the patient, which helps distribute the suspension of the prosthesis over the whole surface of the limb. As the wearer sweats, losing fluid causes the volume of the residual limb to decrease, which correspondingly alters the fit of the residual limb within the socket. Therefore, there is also a need to improve the consistency and reliability of the fit between the residual limb and the socket.
Many existing valve systems include components protruding from the socket, making it cumbersome and uncomfortable to wear, while also increasing the chance it may snag onto foreign objects. By not keeping a low profile, there is also a greater likelihood of the valve system being damaged. Damaging the valve would cause the air pressure within the socket to no longer be properly maintained, and the vacuum suspension it provides to the residual limb would ultimately fail. There is a clear need for an improved pressure regulation system that is not burdensome or uncomfortable for a user, and which maintains a low profile.
Using a conventional valve system alone may not be an effective or efficient way to expel excess air from within the socket. Instead, it is a goal behind embodiments of the disclosure to provide a valve system with an improved pump to create the desired vacuum effect. Including such a pump would ensure a sufficient amount of air is expelled from the socket to create the desired suction.
Current pumps used with prosthetic sockets have disadvantages, including their size, weight and difficulty of use. For many patients, the time-consuming steps involved with operating the pump combined with the cumbersome placement and unreliability of accurately regulating pressure convinces them to avoid using prostheses entirely. There is therefore a need to provide an easy and quick way of adjusting the fit of the residual limb within the socket, while making the prosthesis easier to don and doff without sacrificing comfort.
It can be seen from the foregoing there are many needs for improving on the drawbacks of conventional vacuum suspension systems for attaching to prosthetic sockets. The embodiments of the present disclosure address these aforementioned shortcomings of known prosthetic systems.